Hot-air engine



Au 17; 1943. T, F, THOMPSON 2,326,901

HOT AIR ENGINE Filed Oct. 7, 1940 2 sheets -shet 1 JANA f mm M, Mvm

Aug. 17, 1943. T. F. THOMPSON 2,

HOT AIR ENGINE Filed Oct. 7, 1940 2 sheets-sheet 2 MM, 304, wvm

IS on the cylinder ll. Similarly, flange I6 on cylinder H is attachedtofiange' IT on the heating cylinder l2. The cooling cylinderjis provided on the outside with: fins I8, preferably integral which lies adjacent the cooling cylinder, so as to form an almost continuous cooling surface over v the whole length of the cooling ,cylinderand over as much as one-quarteror more of thelen gth of the heating cylinder. v

Working piston maybe machined-as in the case'of the present day gasoline engine pistons, V

and may be provided with one or more piston rings 2| to check loss of compression and prevent oil from the crankcase rising into the air space above the piston. Connecting rodlz is attached by any known means, asfor example by wrist pin 23 to thepiston and by crank pin 24 to the crankshaft 25. Crankshaft '25 protrudes from the crankcase In .at both endsf'to one of which is attached a flywheel 28 and a pulley 29] or any otherknownmeans used to transfer the power. At the other end of crankshaft is an eccentric 3|, to which is pivotally attached arod 33'by means of bearing 32. It will be noted-that the eccentric bearing 32 and the crankpin'24 are dis posed at an angleof 90", I Enclosing the eccentric and bolted orotherwise attached to' the crankcase is a casing 34 which may contain oil to bathe the. eccentric. At the point where the rod 33 emerges from the casing 34, the casingis "aper tured to allow for the swinging motion of the rod.

sleeve 35, preferably of leather, enclosing the rod 7 to Drevent'the splashing of oil from the casing.

V Th transfer piston38, which i's preferably a hollow, arcuate tube closedat both ends so as to minimize weight, and conforming to the toroidal v shape of thecylinder I2, is mounted on lever 39 for reciprocation in cylinder l2, clearance being provided between the piston and the cylinder wallto allow" passage 'of-the' air past the piston and to eliminate friction. The wall of cylinder]! and the side's of piston 33 therefore'do not need to be perfectly machined, ,sincethere is no contact beminimized? The heating cylinder I2 maybe constructed of two similar halves with smallflanges inder. Keyed or otherwise rigidly secured to one end of shaft 41 is another lever 50 (shown in outline in Figure l) which in turn is pivotally secured torod 33 as by means of pin 5 I;

A rnodification -of the, invention is shown in Figure 5 where twoheatingcylinders have been substituted'for the heating cylinder l2. The two with th cylinder. wall, Th fins a e l o cylinders are madein three pieces,'two similar formed on thatportion'of the heating cylinder I2 7 outside ,walls 53 and a central wall 54 common to both; They are held together by ears 4!! and bolts '41 as described hereinbefore, Flanges 56 on the cooling cylinder are larger in this case for they not only'are attached to flanges ill on the heating cylinders but provide an'abutment forthe transfer pistons 55, since the cross-sectional area of the two small pistons isnot coi n cidental with the cross-sectional: area of the cooling cylinder;

In the operationof the engine, as the transfer piston approaches the cooling cylinden'the air is transferred to the hot end of the heating cylinder. The working piston reaches the top of its stroke when the transfer pistonis halfwayin its 1 stroke and 'approachingthe cooling cylinder, due tothe 90 angle between the crank and eccentric pin which operate the" working piston andthe transfer piston respectively. At this point the heated air begins to expand and forces the work'- ing piston down. Whenjthe workingfpiston is about halfway down, the transfer piston reaches the endof its stroke and begins to approach the hot. end of the heating cylinder, thusf initiating 'the transferof hot. airfto the cooling cylinder.

The'cooling of this hot air tends to form'jaslight vacuum which aids the working piston.v in its return stroke. The transfer "piston thenbegins Covering. the aperture and tapering as itr'ises is a v its approach to the cooling cylinder, completing the "cycle. I

Having'thus dcscribedthe invention, what is claimed as new and desired'to be securedjby Letters Patent is: 1 1'. Ina hot air engine, the combination with a working cylinderhaving a working ,piston.

therein, of a heatingcylin'dercommunicating with said working cylinder, said heating cylinder being formed as a segment of attire, and a transfer piston operable in said heating cylinderfor displacing a gaseous medium between the latter and said working cylinder. f v l 2. 1m a hot air engine, the combination with ajworking cylinder having a working. piston therein, of a heating cylinder communicating with said working cylinder, said heating cylinder or ears 40 for the reception of bolts 4| or other securing means. f

At the bas of the'heating' cylinder I2 is a burner plate and below this and surrounding a part of the side wall is a ,heatingcham'ber 45 preferably containing burners 46.

The piston operating lever '39 emerges "through a slot in the cylinder wall and is keyedor other-.

being formed as a'segm ent of a tore, and a trans fer pistoi'roperable in said' heating cylinder for displacing a gaseous'medium between the latter and said working cylinder, said transfer piston being arcuate in form to conform to thec'on- 'figura tio'n'of said heating cylinder, andmeans supporting said transfer piston, for swinging movement about an axis coi'ncidentwith the axis of said tore. v

3. In a hot air engine, the combination with a workingv cylinder having a; working piston therein, of a plurality of arcuate heating cylinders formed as segmentsof tores communicating with said working cylinder, and means associated with said heatingcylinders for displacing a gaseous medium betweensaid heating cylinders and said working cylinder.

, THEODORE F. THOMPSON. 

